When jet-powered aircraft land, the wheel brakes and the imposed aerodynamic drag loads (e.g., flaps, spoilers, etc.) of the aircraft may not be sufficient to achieve the desired stopping distance. Thus, turbofan engines on most jet-powered aircraft include thrust reverser systems. Thrust reverser systems enhance the stopping power of the aircraft by redirecting turbofan engine exhaust airflow in order to generate reverse thrust.
Traditional thrust reverser systems have two distinct operating states: a forward (or stowed) state, wherein the thrust reverser system typically forms a portion a turbofan engine nacelle and forward thrust nozzle; and a reverse (or deployed) state, wherein the thrust reverser system redirects at least a portion of the engine airflow forward and radially outward, to help decelerate the aircraft. The transition between the forward to the reverse state is typically achieved by translating a portion of the nacelle aft. The translating portion of the nacelle is often referred to as the translating cowl, or transcowl, and translating the transcowl aft creates an aperture in the nacelle. Internally, blocker doors are typically deployed synchronously with the translation of the transcowl aft. The blocker doors obstruct forward thrust and generate reverse thrust that discharges through the aperture.
During some phases of flight, it is desired that the engine produce as little forward thrust as possible. For example, during descent the turbofan engine power setting is typically reduced to its minimum thrust setting, often referred to as the “idle” state or the idle power setting. Ideally, the engine should produce zero forward thrust at this idle state, so as to achieve the maximum possible rate of aircraft descent. In practice, the engine still produces a residual amount of forward thrust in the idle state. This residual forward thrust prevents the aircraft from achieving the maximum rate of descent. Consequently, reducing the residual forward or idle thrust during descent is desirable in order to achieve higher rates of descent. Similarly, the engine power setting is typically reduced to idle during a ground taxi. The residual forward or idle thrust may cause the aircraft to accelerate or taxi at a higher rate than is desirable, requiring considerable effort from the pilot in order to maintain a desirable taxi speed.
Accordingly, a system and method for reducing idle thrust in a translating cowl reverser system is desirable. The desired system and method provide a partial deployment, or thrust reverser system intermediate position for a translating cowl thrust reverser system.